Osmotic Patch Microneedle ISF Harvesting
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Solution Overview
Problem
Current microneedle patches for sampling interstitial fluid (ISF) are limited by short-term fluid collection and low fluid volume, lacking a mechanism for long-term biomarker monitoring and prone to external contamination and evaporation losses.
Innovation Solution
A microfluidic monitoring platform combining a microneedle patch with an osmotic patch using glycerogel or hydrogel and a paper microfluidic channel for capillary wicking and evaporation-assisted fluid transport, enabling continuous, long-term ISF sampling and biomarker analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If microneedle patches are used for ISF sampling, then fluid collection is achieved, but the sampling duration is limited and fluid volume is low
Solution Approach 1:
The patent combines microneedle patches with an osmotic patch containing glycerol to create an integrated fluid harvesting system. The osmotic patch generates sustained osmotic pressure to continuously draw ISF through the microneedles, extending sampling duration from minutes to hours while accumulating sufficient fluid volume for biomarker analysis.
Solution Approach 2:
The patent employs osmotic pressure as a hydraulic driving force to transport ISF through the microneedle patch. The high-concentration glycerol in the osmotic patch creates an osmotic gradient that continuously pulls fluid through the microneedles and into the collection chamber, enabling prolonged sampling without external power sources.
2Reliability
If microneedle patches are used for ISF sampling, then fluid collection is achieved, but the system is prone to external contamination and evaporation losses
Solution Approach 1:
The patent uses a hydrogel matrix as a flexible, semi-permeable barrier in the osmotic patch. This hydrogel layer selectively allows water and small molecules to pass while blocking larger contaminants, protecting the collected ISF sample from external contamination while maintaining the osmotic driving force for fluid transport.
Solution Approach 2:
The patent creates a controlled, isolated environment within the patch structure that minimizes exposure to external air and contaminants. The sealed microfluidic channels and evaporation-resistant materials maintain a stable internal atmosphere, reducing evaporation losses and preventing contamination during prolonged sampling.
3Productivity
If osmotic patch with high glycerol concentration is used, then osmotic pressure increases for better fluid withdrawal, but the complexity of the system increases
Solution Approach 1:
The patent designs the osmotic patch to be self-regulating, where the glycerol concentration and hydrogel matrix automatically maintain optimal osmotic pressure without external control. The system self-adjusts fluid withdrawal based on the osmotic gradient, eliminating the need for complex pumping mechanisms or active control systems while maintaining high productivity.
Solution Approach 2:
The patent optimizes the glycerol concentration and hydrogel composition to achieve the desired osmotic pressure threshold. By carefully selecting these parameters during design, the system achieves efficient fluid withdrawal without requiring complex adjustable mechanisms, balancing productivity with simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The platform achieves prolonged ISF sampling and biomarker monitoring, maintaining continuous fluid flow and biomarker collection for hours to days, with glycerogel demonstrating high osmotic pressure for effective fluid withdrawal and evaporation-assisted capillary pressure to sustain sampling.
Implementation Method 1
The osmotic patch generates as chemical potential difference with the hydrate microneedle patch to transport the ISF out of the microneedle patch
Implementation Method 2
a microfluidic or fluid transport film or material channel disposed between the osmotic patch and the microneedle patch, the paper or woven mat, non-woven membrane, or film-based microfluidic channel configured to extract fluid through the microneedle patch via capillary wicking
Implementation Method 3
evaporation-assisted capillary pressure to sustain sampling
Data Source
AI summary
Various examples are provided related to interstitial fluid (ISF) or extracellular fluid (ECF) harvesting and processing. In one example, a microfluidic monitoring platform includes a microneedle patch including microneedles on a first side; an osmotic patch on a second side of the microneedle patch that includes glycerogel or hydrogel equilibrated with glycerin or glucose; and a microfluidic or fluid transport film or material channel between the osmotic patch and the microneedle patch. The channel can extract fluid from the osmotic-microneedle patch complex. In another example, a wearable electrochemical sensing system includes a monitoring platform including a microneedle-osmotic patch, a microfluidic or fluid transport film or material channel, and at least one sensor between the channel; and processing circuitry coupled to the at least one sensor. The processing circuitry can monitor presence of a chemical or biomarker in the fluid based upon signals obtained from the sensor.